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UNITED STATES PATENT OFFICE.

CHESTER E. ANDREWS, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE SELDENCOMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF DELAWARE.

METI-IYL-AMINO-ISOPROPYL-BENZENE-SULFONIC ACID AND PROCESS OF MAKINGSAME.

To all whom it may concern:

1 Be it known that I, Cnns'rnn In. An-

' nnnws, a citizen of the United States, re-

siding at Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inMethyl Amino Isopropyl Benzene-Sulfonic Acid and Processes of MakingSallie, of which the following is a specification.

The present invention relates to a new chemical substance,l-methyl-Q-annino-l-isopropyl-5-sulfonic acid compound of benzene, oramino cymcne sulfonic acid.

In the carrying out of the process comprised in this invention, theCompound amino cymene, (which may be produced as in accordance with theprocess of my copending application Serial No. 191,245. liled September13, 1917, Case A,) or its sulfate, is treated with an excess ofconcentrated sulfuric acid, a sulfuric acid of 98% being preferable,orfuming sulfuric acid. The n'iixture is heated to about 205 (1., untila test portion gives no reaction for the free amin, upon making italkaline. This test may be carried out by adding a test portion to alarge quantity of cold water, and if an oily material separates onmaking alkaline, this shows that the sulfonation is not complete. Theprocess is usually com pletcd,

using 98% acid, in about 10 hours.

As preferred proportions which may be employed, I nientlon about 6 partsof the Specification of Letters Patent.

Application filed September 14, 1917. Serial No. 191,483.

Patented Sept. 2, 1919.

amin to about 5 parts of sulfuric acid of 9S?) strength, or anequivalent (llltllli'lt'); of iumlng sulfuric acid. The reaction mass,

'which is a solid, is lii'st broken up and disduces a solution of thesodium salt of the sulfonic acid, which may be purified by boilin; withbone charcoal iii-.tlecoloi'izing carbon" followed by filtration.

The. filtrate is next acidified and cooled am] the sulfonic acid isthereby precipitatml.

The process produces excellent yields and the purification of theproduct is shown to be substantially complete when a test portion of thefiltrate is found to be colorless. 'lhe sulfonic acid compound issuitable for themanufzuzturc of various other cymcne derivatives.

I claim:

1. 1-meth vl-2-amino--lisopro )yl-bcnzene- .i-sulfonic acid.

A process of making the sulfonic acid derivative of amino cymcne, whichcomprises heating amino cymene with sulfuric acid of not. less thanabout 98% strength until thc-reaetitm mass no longer contains uncombinedamino cymenc. dissolving and neutralizing with an alkali, boiling withcharcoal and thereafter again acidifying to precipitate the sulfonicacid.

In testimony whereof I aflix my signature.

CHESTER E. ANDREWVS.

